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Marine benthic (epilithic) diatom communities along the coast of South Africa: A contribution to their diversity, spatio-temporal variations, and ecology

  • Authors: Cotiyane-Pondo, Phumlile
  • Date: 2023-12
  • Subjects: Marine ecology , Marine biodiversity , Coastal ecology
  • Language: English
  • Type: Doctorate Dissertation , text
  • Identifier: http://hdl.handle.net/10948/62453 , vital:72754
  • Description: Diatoms remain one of the most diverse and ecologically important microorganisms within microphytobenthos. The highly variable South African coastline, comprised of heterogeneous rocky intertidal habitats provides the ideal study area to investigate epilithic microphytobenthos and their associated influential drivers. In South Africa, in-depth taxonomic research on marine littoral diatoms exists, however, quantitative research and knowledge on their abundance, diversity, community composition and distribution remain limited. Thus, the main aim of this research was to explore the spatial and temporal variability of marine benthic (epilithic) diatoms, in relation to the variable physico-chemical conditions in the nearshore intertidal environments along the coastline of South Africa. To achieve this, field-based observational (natural substrata) and experimental (artificial substrata) studies were conducted on selected locations around the coastline, with a large focus on south coast localities. For the Spatial studies, large (i.e., encompassing all three biogeographical regions) and small-scale (i.e., coastal island in the warm temperate region) surveys of epilithic diatom assemblages from natural rocky substrata were conducted. Large-scale investigation results revealed highly variable diatom assemblages, diversity and distribution, with compositional differences observed between the coastal sections (around the coastline). A total of 85 diatom taxa from 31 genera were observed at 15 sites, and the number of taxa varied un-systematically along coastline. Genera with noticeable contribution included Nitzschia, Cocconeis and Achnanthes. On the coastal Bird Island (small-scale), similar variability was observed, but with a much higher diatom diversity and number of rarely observed species (e.g. Actinoptychus senarius (Ehrenberg) Ehrenberg, Cocconeis capensis (Cholnoky) Witkowski, Fragilariopsis kerguelensis (O’Meara) Hustedt, Striatella unipunctata (Lyngbye) Agardh. Seventy-two (72) species from 35 genera were recorded with a varied abundance and diversity around the island. The study also revealed a high contribution of typical benthic diatom species to the surf zone environment around the island. To study temporal variations, medium-term compositional differences on natural substrata were assessed monthly over an annual cycle at a single site. A paucity of diatom material was evident during this study and observations indicated a trend of presence and absence of diatom taxa from the study site. Nineteen (19) diatom genera were identified and those observed, albeit as one or two individual valves, included taxa from several genera including Biddulphia, Diploneis, Campyloneis, Trachyneis and Triceratium. Noteworthy was a seasonal increase in the number of diatom valves encountered, with the highest diatom abundance observed during spring (September) and the genera Cocconeis, Grammatophora and Navicula appearing regularly. To complement the sparse data from the long-term temporal study, a short-term experimental study on artificial substrata (Plexiglass) revealed rapid temporal variations of benthic diatom assemblages. The composition differed spatio-temporally during the experimental period, with fluctuating species occurrences and abundances between the two study sites. The experimental study also revealed the highest number of diatom species observed during this research (134 species belonging to 44 genera). While Cocconeis (13 species) and Nitzschia (9 species) were the dominant genera, 48% of the diatomcomposition was composed of rarely observed taxa that included Cocconeis testudo Giffen, Donkinia sp., Paralia sulcata (Ehrenberg) Cleve. Regarding environmental drivers, the findings indicated the importance of temperature and nutrients in driving diatom spatial abundance and composition along the coastline, as well as the island. However, the potential influence of the interplay between measured variables and unexplored coastal oceanographic processes (e.g., wave action) was noted. Temporally, from the annual study, the nature of the rocky substrate (rock type) rather than environmental conditions was postulated to have been the influential factor that resulted in the low diatom abundance data, however this requires further in-depth investigations on the influence of rock microtopography on microphytobenthos in this region. Contrastingly, the experimental study results indicated environmental variables having varying influences on the diatom diversity indices, however, study site and sampling occasion were revealed as the most important predictors of the observed variability. Further, site-specific biofilm processes, including biological interaction (e.g. grazing), were shown to alter biofilm succession, thus influencing the observed diatom assemblages. Overall, this research provided new and relevant knowledge on the variability of benthic (epilithic) diatom composition, biodiversity and distribution along the coastline, further contributing to our understanding of marine benthic diatoms ecology, their ecological role in the context of intertidal food web and their potential as bioindicators of change in the coastal ecosystems in Southern Africa. , Thesis (PhD) -- Faculty of Science, School of Environmental Sciences, 2023
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  • Date Issued: 2023-12

Mechanical recyclability and biodegradation of biopolymers, biopolymer blends and biocomposite in natural environmental conditions

  • Authors: Nomadolo, Nomvuyo Elizabeth
  • Date: 2023-12
  • Subjects: Polymers , Polymeric composites , Biopolymers
  • Language: English
  • Type: Master's theses , text
  • Identifier: http://hdl.handle.net/10948/62539 , vital:72822
  • Description: The present research aimed at investigating mechanical recyclability and studying the potential biotic and abiotic degradation behaviors of biobased biodegradable polymers in different environmental conditions. The mechanical recyclability tests monitored the effect of multiple reprocessing on the mechanical, thermal, physical, chemical, and morphological properties of poly (butylene adipate-co-terephthalate) (PBAT), poly (butylene succinate) (PBS), poly (lactic acid) (PLA), PBAT-PBS blend, and PBAT-thermoplastic starch (TPS) composite. Low-density polyethylene (LDPE), a conventional non-biodegradable plastic, was also monitored for comparison studies. The mechanical recyclability tests were carried out by eight melt extrusion cycles using twin-screw extrusion and injection molding processing techniques. Tensile testing, impact analysis, melt flow index test (MFI), differential scanning calorimetry (DSC), thermogravimetry (TGA), dynamic mechanical analysis (DMA), Fourier Transform Infrared Spectroscopy (FTIR) and scanning electron microscopy (SEM) techniques were employed to monitor the effect mechanical recycling at each melt extrusion cycle. Tensile and impact strength results showed that PBAT and PBAT-TPS biocomposite were mechanical recyclable for at least eight cycles and this was comparable to LDPE recyclability performance. In contrast, neat PBS, PLA, and PBAT-PBS blend were found to be melt extrudable only up to six cycles as the mechanical properties declined with the increase of reprocessing cycles. MFI tests suggest that molecular weight of PBAT and PBAT-TPS were not significantly affected by multiple extrusion cycles while the melt flow properties of PBS, PLA, and PBAT-PBS samples were affected from third cycle. DSC, TGA, and DMA demonstrated that PBAT and PBAT-TPS were more thermo-mechanically stable than PBS, PLA, and PBAT-PBS blend. FTIR spectroscopy results showed that the chemical structure of both PBAT and PBAT-TPS were unaffected by the multiple recycling cycles typically indicated by characteristic peak vibrations bands of C=O and C-O around 1710 cm-1 and 1046-1100 cm-1, respectively. SEM micrographs of PBS, PLA, and PBAT-PBS clearly evidenced the degradation of the biopolymers by severely fractured morphology as a result multiple reprocessing cycle.The rate of aerobic biodegradation for PBAT-PBS and PBAT-PLA blends was examined under controlled home and industrial composting using the CO2 evolution respirometric method. FTIR, DSC, TGA, X-ray diffraction analysis (XRD), and SEM were employed to monitor the changes in the structural, chemical, thermal, and morphological characteristics of the biopolymer blends before and after biodegradation. The biodegradation tests showed that PBAT-PBS and PBAT-PLA blends exhibited higher degradation rates under industrial composting conditions than under home composting conditions. The increased intensity of hydroxyl and carbonyl absorption bands on the FTIR spectra confirmed that the biodegradation process occurred. SEM revealed that there was microbial colony formation and disintegration on the surfaces of the biopolymer blends. Moreover, abiotic degradation results suggested that thermal and hydrolytic conditions influence the degradation process than sunlight exposure. Additionally, aquatic biodegradation results showed that PBAT-PBS blend and PBAT-TPS composite undergo a higher rate of biodegradation as compared to PBAT, PBS, and PLA.The results obtained from this research work conclude that biobased biodegradable polymers can be mechanically recycled, and they are suitable for biological degradation in industrial composting, home composting and marine environment. , Thesis (MSc) -- Faculty of Science, School of Biomolecular and Chemical Sciences, 2023
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  • Date Issued: 2023-12

Psychobiographical study of Daisy De Melker

  • Authors: Moodley, Kerisha
  • Date: 2023-12
  • Subjects: Psychobiographical study , Antisocial , Personality dynamics
  • Language: English
  • Type: Master's theses , text
  • Identifier: http://hdl.handle.net/10948/62913 , vital:73067
  • Description: Daisy Louisa C. de Melker, born on 1 June 1886, was a qualified nurse who is famously known to have poisoned two husbands with strychnine in order to receive life insurance money while living in Turffontein, Johannesburg. Later on, she poisoned her only son with arsenic for reasons which are still unclear, and he passed away soon after. She is notoriously known in history to be the second woman to have been hanged in South Africa due to receiving the death penalty. The primary aim of the study is to explore the life of de Melker to gain an understanding of her personality development, with the aim of acquiring insight into the motivation behind her behaviour. The secondary aim includes exploring apparent Cluster B personality traits. The study is exploratory-descriptive in nature and the subject was chosen through purposive sampling. The study uses a qualitative, psycho-biographical, single-case research design to study De Melker, in order to explore and describe the personality development of her from the theoretical perspectives of Kernberg’s Object Relations Theory. This specific theory was chosen as it allowed the researcher to explore Daisy de Melker’s early childhood and upbringing that impacted the formation of ‘internal representations’ of herself and other people. The theory suggests that when there is a lack of integration of object relations, which is made up of internal and external representations, it may result in the development of a personality disorder, as it places a focus on relationships being more crucial to personality development than individual drives and abilities. Data was collected by triangulating multiple sources of information. Miles and Huberman’s (1994) strategy were used to analyse the data according to three steps, which include data reduction, data display, and conclusion drawing and verification. The significance of doing a psychobiography study lies in merging of personality psychology and historical evidence which represents a growing field in the realm of biography and provides insight into personality development through a theoretical framework. , Thesis (Ma) -- Faculty of Health Science. 2023
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  • Date Issued: 2023-12

Pyrolysis of algal biomass and coal in a rotary kiln reactor: Pyrolysis behaviour, product distribution and kinetic analysis

  • Authors: Nyoni, Bothwell
  • Date: 2023-12
  • Subjects: Algal biofuels , Biomass energy , Coal -- South Africa
  • Language: English
  • Type: Doctorate theses , text
  • Identifier: http://hdl.handle.net/10948/62550 , vital:72823
  • Description: There are two primary reasons why the global economy is gradually reducing its dependence on coal as an energy source. Firstly, coal reserves are finite, and while some argue that current reserves will last for generations, the reality is that coal is a non-renewable resource. Secondly, the emissions associated with coal usage have adverse effects on both the environment and human health. While European countries have adopted seemingly aggressive strategies to replace coal and other fossil fuels, South Africa and other developing nations face economic constraints that limit such actions. Fortunately, there are more conservative approaches that can be employed, one of which involves a gradual introduction of renewable energy sources into the energy grid. Wind, solar, and biomass currently stand as the major renewable energy sources under consideration. However, it's worth noting that the intermittent nature of wind and solar energy production poses a significant challenge. Biomass holds the potential to replace coal in retrofitted coal-fired plants. However, the unchecked utilisation of biomass can lead to deforestation and have adverse effects on the human and animal food supply chain, as many essential food items are derived from plants. The debate over using biomass as a fuel source, especially when some types of biomasses can serve as food for humans and animals, has been a subject of ongoing discussion. Furthermore, biomass exhibits a lower energy density when compared to coal. Combustion stands as the primary technology for converting coal into energy and is widely used in most coal-based power plants. Gasification, on the other hand, has been employed for years in South Africa as a coal-to-liquids technology to supplement transportation fuel requirements and reduce reliance on crude oil imports. Pyrolysis, too, has found application as a key method for obtaining high-energy coal char, serving both as an energy source and a reducing agent in blast furnaces for the steelmaking industry. Pyrolysis technologies are gaining popularity in biomass-to-liquids processes due to their simplicity. Currently, there is growing research interest in simultaneous pyrolysis of coal and biomass. The study presented in this thesis focuses on investigating the pyrolysis of Scenedesmus algae biomass and low-grade coal in a small-scale rotary kiln, with particular emphasis on the synthesised liquid products. Algae represent a unique type of biomass that can be cultivated in photo-bioreactors with minimal use of agricultural land. This suggests significant potential for large-scale cultivation of algae, and ongoing efforts are exploring strategies for the mass production of algal biomass.Firstly, pyrolysis studies were carried out via thermogravimetric analysis instruments. It was revealed that because of algae’s considerably higher volatile content and lower carbon content when compared to coal, the pyrolysis process of algal biomass occurred at a faster rate. The highest pyrolytic reactivity of algae was 0.41 mg/min occurring at approximately 290 ᵒC in comparison with coal’s 0.06 mg/min occurring in the approximate temperature range of 550 – 600 ᵒC. The magnitude of the reactivity of the blends depended on the coal/algae ratios used. Furthermore, kinetics analysis revealed that the overall pyrolytic decomposition of coal followed 2nd order kinetics with an activation energy of 81.8 kJ/mol. The decomposition of algae and coal-algae blends occurred in two stages; the first stage decomposition followed 2nd order kinetics with activation energies in the range 130.3 – 145.5 kJ/mol. The second stage decomposition of algae followed 1st order kinetics with an activation energy of 27.3 kJ/mol, whilst coal-algae blends followed 2nd order decomposition with an activation energy range of 69.4 – 74.2 kJ/mol. Secondly, pyrolysis studies were carried out in a rotary kiln reactor wherefrom the char products were collected, and pyrolytic gases condensed to obtain pyroligneous liquid. It was found that the composition of oils synthesised from the pyrolysis of coal was rich in paraffins (52.6 % at 550 ᵒC), however the yield of oil from the pyrolysis of coal was low (6.9 %). Oils from algae and coal-algae blends were dominated by alcohols, fatty acids, fatty acid esters and poly-cyclic aromatic compounds. For example, the most abundant compounds in algae oil produced at 550 ᵒC were fatty acid esters (28.8 %), alcohols (17.6 %), fatty acids (10.8 %) and unsaturated aliphatics (10.7 %); the oil yield obtained from pyrolysis of algae was 40 %. The yields and composition of oils obtained from coal-algae blends were linked to individual contributions from coal and algae, especially at 550 ᵒC; however, the contributions were not proportional due to synergistic effects. This kind of study will contribute to the already existing but limited literature on coal-algae pyrolysis. Furthermore, this study demonstrates the potential of using low-grade coals (an abundant resource in Southern Africa) in conjunction with algal biomass (a renewable resource), in large-scale synthesis of liquid fuels and valuable chemicals via a simple pyrolysis process. , Thesis (MSc) -- Faculty of Science, School of Biomolecular & Chemical Sciences, 2023
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  • Date Issued: 2023-12

Spatial patterns of human-elephant conflict and elephant space-use in Liwonde National Park, Malawi

  • Authors: Voges, Mignon
  • Date: 2023-12
  • Subjects: Human-animal relationships , Wildlife management -- Malawi , Wildlife conservation -- Malawi
  • Language: English
  • Type: Master's theses , text
  • Identifier: http://hdl.handle.net/10948/62721 , vital:72933
  • Description: Human-wildlife conflict (HWC) is a prevailing issue worldwide, threatening the livelihood of the affected human communities, and the persistence of wildlife populations and habitat. Human-elephant conflict (HEC) is particularly challenging, given the damage or harm these large animals can cause to human communities. Moreover, HEC threatens the safety of elephant populations as elephants can be injured or killed when people retaliate. Several studies have therefore been conducted to investigate HEC spatiotemporal patterns in order to better understand it and to develop mitigation measures. These studies predominantly used non-spatial statistics or global regressions to investigate HEC patterns and drivers. The general understanding of HEC patterns and drivers are therefore based on general predictions derived from global regressions that assume stationarity of the relationship between HEC and its drivers across the landscape. Previous studies using global regressions may therefore have missed or misidentified important drivers of the spatial patterns, making the resultant global regression models misleading. The aim of this study was therefore to investigate the spatiotemporal patterns and drivers of HEC adjacent to Liwonde National Park using spatial analytical tools that account for the spatial nature of the data and the spatial variation in conflict drivers across a landscape. Using a Geographically Weighted Regression, I identified vegetation quality, season, and distance to seasonal water as drivers of HEC hotspots adjacent to Liwonde. HEC was more intense in areas with higher quality vegetation (compared to vegetation quality inside the Park) and areas that were closer to seasonal water. The relationship between HEC hotspots and these drivers varied at the patch-level and according to season. My findings suggest that HEC is more complex than the general patterns described with global regressions. The localized patterns and drivers of HEC hotspots identified, reflect trade-off between elephants securing rewards (crops), while reducing risks (encountering humans), as expected under forage optimality models. The understanding of elephant adaptation and trade-offs in human landscapes gained from my study, along with the approach I have adopted, can be applied to other HEC study sites, and help guide HEC management in Liwonde. This approach can also be applied to analysis of other forms of HWC, greatly improving HWC mitigation. , Thesis (MSc) -- Faculty of Science, School of Natural Resource Management, 2023
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  • Date Issued: 2023-12

Statistical analysis of hydrogeochemical data from fractured rock aquifers around Beaufort West, South Africa

  • Authors: Berkland, James
  • Date: 2023-12
  • Subjects: Groundwater -- South Africa -- Beaufort West , Hydrogeology -- South Africa -- Beaufort West , Aquifers -- South Africa -- Beaufort West
  • Language: English
  • Type: Master's theses , text
  • Identifier: http://hdl.handle.net/10948/62442 , vital:72736
  • Description: Knowledge surrounding the procedures and protocols related to groundwater sampling are currently limited. In particular, the sampling of radioactive elements from fractured rock aquifers is poorly understood and in need of further research. The aim of this study is to provide a comparative insight into groundwater sampling methods used for the sampling of major and minor elements as well as trace elements within fractured rock aquifers in the immediate vicinity of Beaufort West. The influence of sampling source, seasonality, and vertical flows on sample results are observed. Furthermore, the importance of historical datasets is raised. Aims of this study were achieved by making use of historical data from numerous studies that were conducted near the Karoo town of Beaufort West. Potential profitable uranium deposits saw a great influx of research into the geology, topography, climate and hydrogeology. Synthesising data from these historical research papers has provided valuable information regarding the influences of sampling procedures on the results. A total of 695 well data samples were analysed from four studies collected from farms around Beaufort West. The importance of adequately purging a well prior to sampling cannot be stressed enough. There are minimal chemical differences between sampling boreholes and wind pumps, however there was a noticeable difference in the inter-relationships between major chemical elements. Groundwater samplers were found to be contaminated with Zinc and Copper attributed to wind pump fittings. Boreholes were also analysed to observe any changes in depth. Sodium, temperature and uranium had little to no changes with depth due to the homogenous nature of the borehole water. Principal component analysis was conducted on 159 groundwater samples comprised of 13 variables. These samples were reduced to four principal components (PC) which explained a total of 91.09% of the total variance. Factor one explained 61.99% of the total variance and was strongly associated with water-type and lithology while factor two (13.57%) shows the potential relationship between molybdenum and uranium as well as possible copper contamination as a result of wind pump and borehole fittings. Further research should be conducted by carrying out multiple sampling procedures on a selection of controlled wells to determine the best applicable sampling procedures. , Thesis (MSc) -- Faculty of Science, School of Environmental Sciences, 2023
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  • Date Issued: 2023-12

Study on the Isixhosa elder’s perspective on mental illness in buffalo city municipality, Eastern Cape, South Africa

  • Authors: Bam, Zimkhitha Yolisa Nokubulela
  • Date: 2023-12
  • Subjects: Xhosa language -- Eastern Cape , Mental illness
  • Language: English
  • Type: Master's theses , text
  • Identifier: http://hdl.handle.net/10948/62827 , vital:73046
  • Description: Generally, the elders in the family are usually responsible for their families, including the care and socialisation of younger members. With the increasing number of mental illness cases being reported, not only in South Africa but the rest of the world, it is imperative to explore what the elderly understand about mental illnesses, given that they may have insights that might be useful. This study aimed to explore the perceptions of elderly members in the isiXhosa community of the Buffalo City Metropolitan Municipality in the Eastern Cape province, regarding their understanding of mental illnesses. The researcher employed an exploratory-descriptive, qualitative design and adopted Lincoln and Guba’s model of trustworthiness. Participants were recruited through the use of snowball and purposive sampling and the data was gathered through one-on-one interviews conducted with elderly isiXhosa individuals. Thematic analysis was used as a means of data analysis, by following data analysis method by Braun and Clarke. The following themes were identified during the study; Limited understanding about mental illness, varied causes of mental illness and a generationally linked understanding of mental illness. The findings reflected the participants understanding of what mental illness is and the causes of it and suggest that more research is required to understand the cultural influences on perceptions of mental illness. , Thesis (Ma) -- Faculty of Health Science, 2023
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  • Date Issued: 2023-12

The coping experiences of healthcare workers during covid-19 pandemic in the Nelson Mandela Bay health district

  • Authors: Matsolo, Vuyiswa
  • Date: 2023-12
  • Subjects: Medical personnel -- Nelson Mandela Bay , COVID-19 pandemic
  • Language: English
  • Type: Master's theses , text
  • Identifier: http://hdl.handle.net/10948/62871 , vital:73061
  • Description: COVID-19 increased in prevalence in 2019 and was declared a pandemic in 2020 by the World Health Organisation (WHO). The pandemic arrived in South Africa in March 2020, and drastically impacted the country. One such impact was to healthcare workers, who had contact with COVID-19 patients on an ongoing basis. Increasing pressure was placed on healthcare workers, and they needed to cope with the demands placed on them during the pandemic. The study aimed to explore and describe the coping experiences of healthcare workers during the COVID-19 pandemic in the Nelson Mandela Bay Health District. To meet this aim, a qualitative explorative descriptive research design was used. Data was collected using individual, semi-structured interviews, with a sample of 10 healthcare workers in the Nelson Mandela Bay Health District. The data was analysed using Braun and Clarke’s (2006) Reflexive Thematic Analysis and the trustworthiness of the study was ensured through Guba’s (1985) model of data verification. Social Constructionism was used as a theoretical framework to conceptualise the findings that emerged from the participants within their socio-historical context. Participants shared their coping experiences which were different from the other but shared particular themes. Participants made use a combination of problem, emotion and meaning focused coping strategies during the peaks while utilising predominantly problem focused coping strategies during the lulls. It became apparent that there were differences in coping in terms of the lulls and the peaks with peaks producing fear and anxiety, while lulls bringing a sense of relief. , Thesis (Ma) -- Faculty of Health Science, 2023
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  • Date Issued: 2023-12

The impact of collaborative writing and scaffolding practices on student writing performance in second language contexts: action research at Midlands State University (MSU)

  • Authors: Hlatshwayo, Primrose
  • Date: 2023-12
  • Subjects: English language -- Context , Writing -- Midlands State University
  • Language: English
  • Type: Master's theses , text
  • Identifier: http://hdl.handle.net/10948/63309 , vital:73248
  • Description: The mixed methods action research study explored how collaborative writing and scaffolding practices impacted on the writing performance of students writing in groups. It sought to establish whether using the collaborative writing (CW) method would enhance the writing performance of 55 social work Midlands State University first-year students. Socio-cultural theory (SCT) was employed as the theoretical basis for the study as it emphasises learning in socially constructed environments in which interaction among peers and teachers leads to learning and construction of knowledge. Through the examination of student interactions in two collaborative writing activities, an analysis of student perceptions of CW, and an assessment of student collaboratively produced texts, the study found that the different peer and teacher scaffolding practices that were employed in the collaborative writing sessions significantly enhanced the students’ writing performance. Regardless of the challenges identified in CW, for example, misunderstandings and meaningless contributions from some group members, the research findings revealed that the student interactions offered scaffolding to support their writing activities. For example, validation feedback, link to previous knowledge and the use of correctional feedback were the scaffolding practices used. In addition, the students were able to collaboratively produce better texts with improved cohesive linking, mechanics, organisation, development, structure and vocabulary. The study contributed to L2 collaborative writing literature as it identifies the different student scaffolding approaches and offers an insight into the collaborative writing process and how it could support ESL writing development. However, the methodology posed some limitations, for example, the use of a questionnaire instead of interviews and recording student interactions in a journal instead of audio recording and, lastly, the researcher struggled to balance research demands and her normal teaching load. The study recommends the monitoring of students in CW groups, facilitation of peer/teacher motivation, establishment of group norms and formation of small groups with a maximum number of six members. , Thesis (MA) -- Faculty of Humanities, 2023
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  • Date Issued: 2023-12

The intimate relationships of Xhosa men from the East London area: perceptions of the role and responsibilities

  • Authors: Ntsaka, Ayanda
  • Date: 2023-12
  • Subjects: Intimate relationship , Indigenous Knowledge
  • Language: English
  • Type: Master's theses , text
  • Identifier: http://hdl.handle.net/10948/62958 , vital:73076
  • Description: Exploring gender identity and ideology can broaden our comprehension of how gender roles and responsibilities are carried out, and how disparities may be experienced. It is critical to explore them, within research, to generate new insight into the views and positioning of individuals, within their intimate relationships. Therefore, the aim of this study was to explore and describe the perceptions of isiXhosa men about their roles and responsibilities in intimate relationships. The study was broken down into three objectives which were: to explore perceptions of their role within their relationship, to explore their perceptions of their responsibilities within their relationship; and to explore factors supporting change within the roles and responsibilities. The study took the format of an exploratory descriptive research design. Ten Xhosa men were selected as participants using snowball sampling, and semi-structured interviews were used to gather data. Data was analysed using Braune and Clarke’s (2006) reflexive thematic analysis. The study came to the conclusion that there are two main roles of Xhosa men in intimate relationship, namely: head of the house; and the provider. Three dominant responsibilities were found to be common among the participants, namely, making all main decisions, providing financial support, and responsibility to safeguard. The study also found factors causing Xhosa men to change their roles and responsibilities in intimate relationsh were unemployment, disrespectful partner, extended family needs, demanding job and inadequate income from work. Lastly, the study concluded that the extent to which the changes of the roles and responsibilities among Xhosa men may affect their intimate relationships include break-ups/divorce, domestic violence, dysfunctional families – fragmentation of families and mental and emotional health issues. , Thesis (Ma) -- Faculty of Health Science, 2023
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  • Date Issued: 2023-12

The use of a novel chemical system towards improving waste tyre pyrolysis and the quality of waste tyre pyrolysis products

  • Authors: Tsipa, Phuti Cedric , Iwarere, Samuel
  • Date: 2023-12
  • Subjects: Tires -- Recycling , Rubber chemicals , Rubber, Reclaimed
  • Language: English
  • Type: Doctorial theses , text
  • Identifier: http://hdl.handle.net/10948/62666 , vital:72912
  • Description: Pyrolysis process is one of the most efficient methods in the waste tyre recycling sector at this moment, hence the attention it is receiving. However, this process has some limitations, with the main one being that it is non-conventional and typically energy intensive. In addition, its resultant products have been reported to have significantly poorer properties relative to their virgin counterparts, making it difficult to incorporate them in the mainstream of raw materials. For instance, waste tyre pyrolysis oil typically has poor fuel properties, high sulfur content, high amount of polycyclic aromatic hydrocarbons (PAHs) and strong unpleasant odour; on the other hand, the quality of the recovered carbon black is dependent on the feedstock and the pyrolysis process conditions. Hence the need for further research and development to make the process effective and improve the quality of resultant products. The aim of this research project was to study the impact of pre-pyrolysis treatment of tyre crumbs and post-pyrolysis treatment of the oil using a novel chemical system on the quality/composition of the resultant products. In addition, the study compared the impact of pre- and post-pyrolysis treatments on the optimum pyrolysis time and temperature (energy). The equipment employed in this study included a vertical fixed bed pyrolysis pilot reactor (modified to suit the reaction/experiment) as well as characterization techniques such as fourier transform infrared (FTIR), elemental analysis (carbon, hydrogen, nitrogen and sulfur – CHNS analysis), gas chromatography coupled to mass spectrometer (GCMS), gas chromatography coupled to flame photometric detector (GCFPD), thermo-gravimetric and derivative analysis (TG/DTG isothermal analysis, and proximate analysis) and scanning electron microscope (SEM). The highlight of the findings is that chemically pre-treating tyre crumbs with a mixture of protonic acid and organic solvent before pyrolysis significantly lowered the temperature required to pyrolyze them, from around 400-500 ℃ to 100-115 ℃. This meant that by using the chemical treatment on waste tyres a lot of energy can be saved. In addition, the sulfur content in the oil fraction was reduced from a total of 1.7 wt% to a total of about 0.2 wt%. This also showed that the contaminants in oil were significantly reduced. The oil was condensed into three (3) collectors for fractionation; in collector 2 was about 54 % of the total oil with sulfur content of about 0.015 wt%. The PAHs amounts were also lowered, as literature indicated that PAHs are mostly formed at around 600-700 ℃. It was also found that the oil produced from post-pyrolysis treatment of oil has a petroleum-like smell, whereas the pre-pyrolysis treated oil has a tyre-like pungent odour. Furthermore, the post-pyrolysis treated oil contains higher contents of alkanes and benzene, toluene, xylene (BTX). Findings of this study have a profound potential impact on the waste tyre recycling industry; for example, reduced production energy cost due to lowered temperature required for pyrolysis, improved quality of the products such as lowered sulfur and PAHs content as well as improved quality of the residual char and odour. , Thesis (PhD) -- Faculty of Science, School of Biomolecular and Chemical Sciences, 2023
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  • Date Issued: 2023-12

Traditional birth attendants’ perceptions of their role in caring for women during childbirth in the Nyandeni sub-district

  • Authors: Sinxi, Sisanda
  • Date: 2023-12
  • Subjects: Traditional Birth , Midwives--Nyandeni sub district
  • Language: English
  • Type: Master's theses , text
  • Identifier: http://hdl.handle.net/10948/63012 , vital:73082
  • Description: The role of Traditional Birth Attendants (TBAs) has been within remote communities for a long time. TBAs remain a major health resource in rural communities in developing countries as well as in some parts of urban areas. South Africa is a long way from effectively utilising TBAs as a community resource to enhance access to maternity services. This qualitative study, with an explorative, contextual, and descriptive design, included ten (n=12) TBAs aged between 38 and 56 years who met the inclusion criteria and were interviewed for the study. The objective of the study was to explore and describe TBAs’ perceptions of their role in caring for women during childbirth in the Nyandeni Sub-district. Data for this study was collected using face-to- face and individual semi-structured interviews, and field notes. Recorded data was transcribed verbatim and analysed using thematic analysis. Three main themes emerged, namely: TBAs perceive their role in caring for women as an essential service to women in the community; they believe that they possess the knowledge to conduct deliveries safely; and acknowledge that collaboration with the Department of Health could strengthen rural midwifery services. , Thesis (Ma) -- Faculty of Health Science, 2023
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  • Date Issued: 2023-12

Medication adherence: a review of policy and education in South Africa

  • Authors: Nyoni, Cynthia Nomagugu
  • Date: 2023-10-31
  • Subjects: Patient compliance South Africa , Drugs Administration Study and teaching (Higher) , Pharmacist and patient South Africa , Pharmaceutical policy South Africa , Patient education South Africa , Medication adherence
  • Language: English
  • Type: Academic theses , Master's theses , text
  • Identifier: http://hdl.handle.net/10962/419548 , vital:71653
  • Description: Medication adherence is a patient's active and voluntary participation in following all the recommendations and instructions agreed upon with a health care provider such as a pharmacist. Adherence is a multidimensional phenomenon determined by the interplay of five factors: patient-related factors, socioeconomic factors, condition-related factors, health system-related factors, and therapy-related factors. Medication non-adherence is a problem in many countries, especially low to middle-income countries, including South Africa (SA). In low to middle-income countries, non-adherence is often worse due to insufficient health resources and inequities in access to health care. Medication adherence is a global problem and has raised the need for research and review. Many healthcare professionals, especially pharmacists, have an essential role in promoting medication adherence. This study described, explained and evaluated the policies in SA relating to the pharmacist's role in promoting medication adherence. Furthermore, it described medication adherence-related education at four universities in South Africa. The study was qualitative, and a two-phased approach was employed. In the first phase, a document analysis of the pharmacist’s role in supporting medication adherence was conducted as described in national policies and guidelines in SA. A total of 38 documents were analysed, including critical documents such as the South African Pharmacy Council Good Pharmacy Practice Manual and Associated SAPC rules (GPP) manual, National Drug Policy (NDP), Standard treatment guidelines (STGS) and Integrated Adherence Guidelines. The READ approach was used in conducting the document analysis and involved (1) preparing materials, (2) extracting data, (3) analysing data, and (4) distilling findings. The critical roles of pharmacists in medication adherence that were identified were in drug use, supply and management, dispensing, therapeutic drug monitoring, pharmacovigilance, pharmaceutical care, and special programmes like antimicrobial stewardship (AMS), multi-drug resistant tuberculosis (MDR-TB) care and antiretroviral treatment (ARV) and chronic conditions. In the second phase, in-depth interviews were conducted with lecturers to investigate and report on the inclusion of medication adherence and the teaching thereof in the curriculum of the Bachelor of Pharmacy Degree (BPharm) in pharmacy institutions in SA. Purposive sampling was used, and seven lecturers from four different institutions participated in the interviews. The interviews were conducted via Zoom® and were transcribed and analysed using thematic analysis. The teaching of medication adherence in the BPharm curriculum of the respective interviewed pharmacy institutions was explored. It was found that the topic of medication adherence was integrated into all subjects throughout the curriculum and not taught as a formal course. Although medication adherence is taught in many disciplines, it is predominantly in pharmacy practice in all institutions. The teaching methods identified included lectures, case studies, workshops, tutorials, practicals, readings, tasks, assignments and videos. The perceived effectiveness of the teaching methods was explored; also the time spent teaching medication adherence and the time efficiency. Student understanding, interest and engagement with the topic were explored and determined through their assessment performance and class attendance. In conclusion, from policies, the pharmacist's role concerning adherence is indirectly integrated into many other roles. It is often not distinguishable from that of other healthcare professionals and is often implied as part of a more generic role. Pharmacy students are educated on medication adherence and the skills and knowledge required to identify, monitor and support patient adherence to therapy. However, there is scope to increase the course content on medication adherence. There is a need to identify effective strategies for preparing pharmacists to assist patients in medication adherence. , Thesis (MPharm) -- Faculty of Pharmacy, 2023
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  • Date Issued: 2023-10-31

A case study of role conflict experienced by middle management during organizational change

  • Authors: Sepeng, Mugabe
  • Date: 2023-10-13
  • Subjects: Role conflict , Change management , Middle managers , Middle management , ISO 9001 Standard Implementation of
  • Language: English
  • Type: Academic theses , Master's theses , text
  • Identifier: http://hdl.handle.net/10962/419189 , vital:71624
  • Description: This research investigation is based on continuous improvement changes arising from - and related to - ISO 9001 implementation at Sundays River Citrus Company (SRCC), which is one of the biggest packers, marketers, and exporters of citrus fruit in South Africa. The Board of SRCC adopted ISO 9001 to ensure organizational efficiency and sustainability while improving quality control, customer service, teamwork and leadership. However, research indicates not all organizations that have Implemented ISO 9001 realize the intended benefits. While no research was available on the citrus agriculture industry, research in the tourism industry indicates that not only did some companies not realize the expected benefits, but also incurred substantial investment costs. It is estimated that approximately thirty to ninety percent of change initiatives fail to meet their objectives, and research studies also indicate that middle managers play a critical role that can influence the outcomes of a change project. However, Balogun (2003) indicates that middle managers play a complex role and are exposed to role conflict, which can influence the outcomes of change initiatives. In this context, this research study aimed to investigate the role conflicts experienced by middle managers during the process of an ISO 9001 continuous improvement change. The study draws on role theory, applying it to their management of change. The following role conflict types were investigated: (1) intra-sender conflict, (2) inter-sender role conflict, (3) inter-role conflict, (4) role ambiguity and (5) role strain. The research approach is qualitative, and has adopted a post-positivist paradigm, utilizing a deductive qualitative method. The study adopted a case study approach. Data was gathered mainly from interviews and supported by organizational documents. Semi structured interviews were conducted with questions formulated through the use of the coding manual (See Appendix C) to ensure alignment of data collection with the research propositions derived from literature. A deductive thematic analysis method was used to analyze the interview data. The research findings confirmed that during continuous improvement change, as middle managers strived to satisfy the incompatible expectations of role senders (mainly senior and junior managers), they experienced the five role conflict types. The study findings also indicate that middle managers experience conflicts due to the incompatible expectations of other role senders such as quality and marketing departments. The findings suggest that middle managers are managing these conflicts, but notes that they do require some assistance and support from senior management. The study concludes with managerial and research recommendations. , Thesis (MBA) -- Faculty of Commerce, Rhodes Business School, 2023
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  • Date Issued: 2023-10-13

A comprehensive review of the taxonomic diversity within the freshwater catfish genus Parauchenoglanis (Siluriformes, Auchenoglanididae)

  • Authors: Sithole, Yonela
  • Date: 2023-10-13
  • Subjects: Uncatalogued
  • Language: English
  • Type: Academic theses , Doctoral theses , text
  • Identifier: http://hdl.handle.net/10962/402992 , vital:69912
  • Description: Thesis embargoed. To be released early 2026. , Thesis (PhD) -- Faculty of Science, Ichthyology & Fisheries Science, 2023
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  • Date Issued: 2023-10-13

A council of women

  • Authors: Sobekwa, Lelethu Anathi
  • Date: 2023-10-13
  • Subjects: Uncatalogued
  • Language: English
  • Type: Academic theses , Master's theses , text
  • Identifier: http://hdl.handle.net/10962/435988 , vital:73218
  • Description: This thesis comprises extracts of life writing written in short prose forms. The work reads like a novella and I have been inspired by Margaret Patton Chapman’s approach to the novella, where she condenses “the telling of a long story time wise”, so that a story occurring over two years can be told over two pages. The thesis explores relationships between mother, daughter, grandmother and granddaughter, each with different life experiences and each teaching the next generation about how to navigate life as politically, socially and economically disadvantaged women. I have also drawn inspiration from authors such as NoViolet Bulawayo who explores the hypocrisies of the church and the government in We Need New Names. In Kate Bernheimer’s “Fairy Tale is Form, Form is Fairy Tale” she writes about fairy tales adopting “intuitive logic” or telling in the form of “this happens and then this happens” while the explanation behind the events is not spelt out but rather exists between the lines. My thesis adopts this style of writing by allowing the reader to understand what is being said without over-simplifying. To this end, I have used the concept of place modelled on Es’kia Mphahlele’s In Corner B, where characters are inscribed in relation to the spaces they inhabit. , Thesis (MA) -- Faculty of Humanities, School of Languages and Literatures, 2023
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  • Date Issued: 2023-10-13

A distributed approach to leadership in an academic department in a South African university: an exploratory case study

  • Authors: Haufiku, Kenneth David
  • Date: 2023-10-13
  • Subjects: Universities and colleges Administration , Education, Higher South Africa , Distributed leadership , College department heads South Africa , School management and organization South Africa , Group decision making
  • Language: English
  • Type: Academic theses , Master's theses , text
  • Identifier: http://hdl.handle.net/10962/419748 , vital:71672
  • Description: The Head of Department (HOD) position at a university has traditionally been viewed as an individual construct. However, due to the demanding nature of such a position, it is not sought-after, as it remains exclusive and unappealing to many academics. Moreover, it is a position that does not encourage inclusive leadership. Tension and role ambiguity are known to arise between the scholarly project on the one hand and management and administrative matters on the other. To address challenges associated with this singular leadership position, an academic department at a South African university adopted a distributed leadership approach in their department as a research experiment. My study was based on this research experiment. I designed this research as an exploratory case study, guided by a socio-cultural conceptualisation of distributed leadership that included a leader-plus and a practice aspect, defined as a product of the interactions of school leaders, followers and their situation. This qualitative case study aimed to describe and explain how a distributed leadership approach was understood and practised in an academic department. It also investigated the enablements and constraints of the approach. Data were generated through document analysis, observation, and individual and focus group interviews. The participants in this study included the departmental leadership team and the department’s academic and administrative staff. Unfortunately, my study took place during the global COVID-19 pandemic and national lockdowns. I had no choice but to adapt my data generation methods due to lockdown restrictions. As a result, most data generation was done via online communication. The study used inductive and abductive analysis to make the data meaningful to the reader. The findings revealed that different participants had different ideas about distributed leadership. Distributed leadership was understood as a socio-cultural practice rather than an individual practice with multiple leaders in relational practice. In addition, this approach was understood as a way of developing and sharing expertise by encouraging teamwork, collegiality and collective decision-making which aligns with the notion of democratic decision-making which creates a platform for the enablement of leadership in others. The study further explored how distributed leadership was practised. The findings were that the HOD position, usually a one-person role, was reconceptualised as a HOD team comprised of three academics and the departmental administrator. The HOD team divided the work among themselves, and this was done according to each individual’s expertise. In addition, leadership within the academic department was not limited to the HOD team but stretched across the department; thus, multiple leaders were evident. Therefore, based on the data, this study discovered that a distributed approach values leadership expertise in others. Consequently, it can be used to promote an inclusive environment in which any organisation member can lead. Inclusivity in the decision-making process was also regarded as a strong practice in the academic department. As a result, this study contends that those in formal positions can develop leadership in others through a distributed leadership approach. Through that, lecturer leadership was enacted through formal faculty and university structures and informally as and when the situation required it. The enablements of this departmental leadership approach included the structural innovation of the Friday check-in as well as the buddy system. These two innovations provided the space for collegiality and the development of voice and leadership. The consultative nature of the HOD team was also viewed as an enablement. Certain factors constrained the distributed leadership approach, one of which was the tension between the hierarchical structure of the university and the more horizontal, distributed leadership approach being piloted in the academic department. In addition to that, another constraint was also very real with the transition to Zoom as an online teaching, learning and supervision platform as a consequence of the COVID-19 pandemic. The final constraint was experienced concerning the department’s history, as it was within a historically White university in South Africa. The effects of this history impacted the departmental culture and, as we know from the literature, institutional culture is extremely difficult to change. Finally, the study concluded that conceptualising distributed leadership as a sociocultural practice with leader-plus and practice aspects provides descriptive language and a solid theoretical and analytical framework for a distributed leadership study. The study makes an important knowledge contribution in the African Higher Education context as limited research has been carried out in this area. Furthermore, in terms of practice, my study serves as a stimulus for leadership discussions that are beneficial to everyone involved in educational institutions as they promote a level of leadership reflexivity, currently absent in many institutions. , Thesis (MEd) -- Faculty of Education, Secondary and Post-School Education, 2023
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  • Date Issued: 2023-10-13

A formative evaluation and critical analysis of an alcohol and pregnancy intervention in the Eastern Cape of South Africa

  • Authors: Graham, Nicola Susan Jearey
  • Date: 2023-10-13
  • Subjects: Uncatalogued
  • Language: English
  • Type: Academic theses , Doctoral theses , text
  • Identifier: http://hdl.handle.net/10962/432541 , vital:72879 , DOI 10.21504/10962/432541
  • Description: Some communities in South Africa have the highest documented rates of Foetal Alcohol Spectrum Disorders (FASD) in the world. Interventions to reduce alcohol consumption during pregnancy are crucial, but evaluations of such interventions are sparse. Formative evaluations are indicated to assist in the development of interventions. Harmful alcohol consumption during pregnancy is undergirded by a range of social injustices, including those imposed by colonisation and patriarchy; a feminist, decolonial approach to evaluations is, therefore, important. A research project, consisting of three arms, examined alcohol use during pregnancy in an under-resourced urban area of the Eastern Cape, and this research was one of those arms. An intervention was being rolled out in this area and I gathered a range of data from it. I engaged in a formative evaluation of it, and I reflect on the difficulties that I encountered in this endeavour. In the bulk of this thesis, I examine the power apparatuses and technologies that were used during the intervention to discursively position pregnant women. My analysis was guided by Foucauldian and post-Foucauldian theories, using Foucauldian Discourse Analysis and simplified Conversation Analysis (CA). Power apparatuses of coloniality, patriarchy, and pastoral power were used in the intervention to construct positions for pregnant women who drink alcohol as ignorant children, sinners, criminals, or “Mommies”. The foetus was constructed as a precious, vulnerable baby, while the person with FASD was constructed as the defiled Other, responsible for societal dissolution. The intervention used various disciplinary techniques to exhort women to follow their dictates. Women were generally compliant with being positioned as ignorant children, which absolved them from any blame for pre-natal drinking. However, some resistance was evident. I then introduce an ethics of care and justice, and I argue that pregnant/newly parenting women need to be positioned within such an ethics, which acknowledges both the universal resources that they require for reproductive freedoms, as well as their particular care needs. I highlight the few times when women were positioned in this way in the data, and I look at how the common positions could be altered or expanded to promote such an ethics. I conclude by arguing that alcohol use during pregnancy cannot be separated from the larger context of the cultural hegemony of alcohol use in some communities, and the social injustices that potentiate this use. I provide suggestions for country-wide policies and interventions, as well as specific FASD prevention programmes, and I argue that a feminist decolonising approach, within an ethics of care and justice, should guide interventions at all levels. , Thesis (PhD) -- Faculty of Humanities, Psychology, 2023
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  • Date Issued: 2023-10-13

A grounded theory study of the identity and career decisions of artistic creative entrepreneurs

  • Authors: Gibson-Tessendorf, Jacoba Cornelia
  • Date: 2023-10-13
  • Subjects: Entrepreneurship , Creative entrepreneurship , Personality and creative ability , Career choice , Creative industries , Identity (Psychology)
  • Language: English
  • Type: Academic theses , Doctoral theses , text
  • Identifier: http://hdl.handle.net/10962/419208 , vital:71625 , DOI 10.21504/10962/419208
  • Description: This research, in the field of creative careers, identity and entrepreneurship, aims to develop a grounded theory to explain the interaction between the phenomena of identity and career decision-making, focusing on Artistic Creative entrepreneurs in the creative industries. Artistic Creatives have unique characteristics and creative identities, presenting unique career opportunities. This research is interested in the different values of Artistic Creatives compared to those of Artistic Creative Entrepreneurs, who often experience a tension between their creative identity and their entrepreneurial identities The methodology used is the Straussian Grounded Theory. A Qualitative Research Approach used interviews to collect data on the careers and identity of Artistic Creative entrepreneurs in an area in the Eastern Cape Province of South Africa. Creative entrepreneurs work in the fields of fine art, design and crafts. The research procedure was recorded in detail, which enhances dependability. Ethics approval was obtained prior to the data collection. The data was analysed through open coding, axial coding and using a Straussian paradigm model. The findings present the values and identity of the Artistic Creative with Artistic Creative Archetypes and the entrepreneurial identities as Artistic Creative Entrepreneur Profiles. The Thesis by JC Gibson-Tessendorf effects of identity and contextual factors on their career patterns, especially as entrepreneurs, are analysed. The contribution that this study makes towards the creation of new knowledge is through, firstly, presenting aspiring creatives with career opportunities that relate to individual values. Secondly, it provides a model of Career Stage Options and Strategies that Artistic Creative Entrepreneurs may follow to either become part-time creative entrepreneurs or use the model as a guide for career planning. The study also developed a substantial theory proposing that the identities of Artistic Creative Entrepreneurs are 1) firstly multiple, 2) flexible and open to change, 2) driven by their values, 3) enacting across the tripartite identity framework, being personal identity, role identity and social identity. The concept of a tripartite of identities was taken from Brewer and Gardner (1996). , Thesis (PhD) -- Faculty of Commerce, Rhodes Business School, 2023
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  • Date Issued: 2023-10-13

A molecular investigation of stem-galling Tetramesa Walker (Hymenoptera: Eurytomidae) on African grasses: applications to biological control

  • Authors: Van Steenderen, Clarke Julian Mignon
  • Date: 2023-10-13
  • Subjects: Uncatalogued
  • Language: English
  • Type: Academic theses , Doctoral theses , text
  • Identifier: http://hdl.handle.net/10962/432565 , vital:72881 , DOI 10.21504/10962/432565
  • Description: South Africa is a larger donor than receiver of alien grasses, where approximately 15% (_ 165 spp.) of the country's native grass species have become naturalised elsewhere. Many of these grasses have become serious invaders, causing significant damage to native species, habitat structure, and ecosystem functioning. Biological control is a sustainable and cost-effective method for the control of invasive weeds, but its application to invasive grasses has been approached with trepidation in the past due to the fears of a lack of host-specific herbivores that may cause non-target damage to agriculturally-important crops. The Tetramesa Walker genus (Hymenoptera: Eurytomidae) is one of three genera in the family that feed exclusively on grasses, and have a record of being host-specific to a particular species, or complex of closely-related congeners. There are over 200 described Tetramesa species, but this taxonomic effort has occurred almost exclusively in the Northern Hemisphere. Only about 2% of the described species are from Africa, with none from southern Africa despite the high diversity of grasses in the region. The low morphological variability between many Tetramesa groups has made identification difficult, where there may in fact be multiple undiscovered cryptic species. This thesis generated genetic sequence data (mitochondrial COI and nuclear 28S) that revealed at least eight native southern African Tetramesa taxa that are new to science, focusing particularly on the assemblages associated with Eragrostis curvula Nees (African lovegrass) and Sporobolus pyramidalis Beauv. and S. natalensis Steud. (giant rat's tail grass) which are alien invasive pests in Australia. Approximately 200 eurytomid wasps were collected and sequenced from 19 grass species across six South African provinces. Additionally, 27 grass species were sequenced using four gene regions (rps16-trnK, rps16, rpl32-trnL, and ITS), which were added to existing sequence data to build a dataset comprising over 700 sequences. Field host ranges and the use of host grass genetic proxies were important in making inferences about the host-specificity of eurytomid wasps of interest. Nine Tetramesa groups appeared to be host-specific to a single grass species, while six Tetramesa were associated with multiple species in a single grass genus. Since S. pyramidalis, S. natalensis, S. africanus, Hyparrhenia hirta, E. trichophora, and Andropogon gayanus are weeds elsewhere, there are at least six potential Tetramesa biological control agents that have been identified. A high diversity of Tetramesa on grasses within the Eragrostis genus was reported, with at least four taxa associated with E. curvula. It is currently uncertain whether these taxa represent different cryptic species or intraspecific populations that are the result of geographic sub-structuring. No-choice host-specificity testing using Tetramesa sp. 4 on E. curvula revealed that the wasp could complete its lifecycle on two non-target African grasses; namely E. plana and E. planiculmis. The wasp was also recorded on other Eragrostis species in the field (namely E. biflora and E. capensis). Using grass genetic sequences obtained in this study, it was found that there are four native Australian Eragrostis species that are more closely related to target E. curvula than to the non-target E. plana and E. planiculmis. This suggests that Tetramesa sp. 4 may not be suitably host-specific for use as a biological control agent. Further host-specificity testing on these native Australian species is required, however, before this insect is ruled out completely. The Tetramesa on S. pyramidalis (Tetramesa sp. 1), and the unidentified Sporobolus species presumed to be S. africanus, were suitably host-specific to be used as biological control agents. Since it was unclear whether some phylogenetic clades were true species or intraspecific populations, which is essential to understand when selecting agents for biological control, a new piece of software, SPEDE-sampler", was developed. It offers users of the Generalised Mixed Yule Coalescent (GMYC) species delimitation model a means of assessing the degree to which sampling effects such as data size and parameter choice can influence species diversity estimates. When applied to the Tetramesa data set, the software assisted in identifying which groups may contain cryptic species, uncovering that the COI marker is affected more by singletons than the 28S marker (i.e. species diversity tends to be overestimated), and confirming putative Tetramesa taxa that could be useful for biological control programmes going forward. This thesis has provided evidence that South Africa contains a diverse assemblage of Tetramesa and other eurytomids that are closely associated with their grass hosts, and that many of these taxa hold promise for grass biological control. This work has also highlighted the importance of integrative taxonomy in the discovery of novel taxa, and that biological control practitioners need to be aware of the caveats of each line of evidence used in the delimitation of putative species. , Thesis (PhD) -- Faculty of Science, Zoology and Entomology, 2023
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  • Date Issued: 2023-10-13
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